The debate has spawned side arguments, such as whether some passive funds are really active management in disguise, or whether the debate should be reframed along the lines of high-cost versus low-cost funds. For an optimal portfolio, think in terms of active and passive. A bundle of new research points to useful strategies for using active or passive funds. The firm, long known for its index products, has $2.9 trillion in index funds, including $757 billion in exchange-traded-fund assets.

Unlike active stock pickers, the best managers from the likes of PIMCO, DoubleLine, Guggenheim and Loomis Sayles have proven track records of adding value for their investors versus a passive benchmark. Look back through my blog and you will see numerous references to some of my favorite funds like the DoubleLine Total Return Bond Fund (MUTF:DBLTX) or the PIMCO Income Fund (MUTF:PONDX). More recently, we have focused on their complimentary exchange-traded fund portfolios via the PIMCO Active Bond ETF (NYSEARCA:BOND) and the SPDR DoubleLine Total Return Tactical ETF (NYSEARCA:TOTL).